The lanthanide contraction is responsible for the fact that:a)Zr and Z...
- Lanthanide contraction is the gradual decrease in the atomic and ionic size of lanthanoids with an increase in atomic number.
- The Lanthanide Contraction is caused by a poor shielding effect of the 4f electrons.
View all questions of this test
The lanthanide contraction is responsible for the fact that:a)Zr and Z...
The lanthanide contraction refers to the decreasing trend in atomic radii across the lanthanide series, which is the series of elements from lanthanum (La) to lutetium (Lu) in the periodic table. This contraction is responsible for the fact that zirconium (Zr) and hafnium (Hf) have about the same radii.
Explanation:
Lanthanide series:
- The lanthanide series consists of 15 elements, starting from lanthanum (element 57) to lutetium (element 71).
- These elements are often referred to as the rare earth elements due to their similar chemical properties and occurrence in rare earth minerals.
Atomic radii:
- Atomic radii refers to the size of the atoms.
- In general, atomic radii decrease across a period (horizontal row) in the periodic table due to increased nuclear charge and stronger attraction between the electrons and the nucleus.
- However, the lanthanide series exhibits a unique trend due to the presence of f-block electrons.
Lanthanide contraction:
- The lanthanide contraction occurs because the additional f-electrons do not effectively shield the increasing nuclear charge from the outermost s-electrons.
- As a result, the outermost s-electrons experience a stronger attraction to the nucleus, causing the atoms to become smaller as you move across the lanthanide series.
- This contraction is most pronounced in the 4f orbitals, which are gradually filled across the series.
Zirconium (Zr) and hafnium (Hf):
- Zirconium (Zr) and hafnium (Hf) are transition metals that are located below the lanthanide series in the periodic table.
- Zr and Hf have similar electron configurations, with Zr having [Kr] 4d2 5s2 and Hf having [Xe] 4f14 5d2 6s2.
- Due to the lanthanide contraction, the radii of Zr and Hf are very similar, despite them being in different periods.
- This similarity in radii is attributed to the shielding effect of the 4f electrons in the lanthanide series, which offsets the increase in nuclear charge and leads to a smaller atomic size for Zr and Hf compared to what would be expected based on their position in the periodic table.
Conclusion:
In summary, the lanthanide contraction is responsible for the fact that zirconium (Zr) and hafnium (Hf) have about the same radii. The contraction occurs due to the poor shielding effect of the additional f-electrons in the lanthanide series, leading to a decrease in atomic size as you move across the series. This contraction extends to elements like Zr and Hf, which have similar electron configurations and exhibit similar radii despite being located in different periods of the periodic table.
The lanthanide contraction is responsible for the fact that:a)Zr and Z...
- Lanthanide contraction is the gradual decrease in the atomic and ionic size of lanthanoids with an increase in atomic number.
- The Lanthanide Contraction is caused by a poor shielding effect of the 4f electrons.